Agronomic Performance, Stability Analysis and Evaluation of Anthracnose Disease Resistance of Common Bean Lines Derived by Marker-Assisted Backcrossing in Uganda

The present study focused on evaluating the agronomic performance, stability, and anthracnose resistance of common bean lines derived through Marker-Assisted Backcrossing in Uganda. Eight marker-assisted selection (MAS) backcross-derived bush bean lines with red seed types, alongside two checks, were evaluated in a randomized complete block design replicated two times in five locations for three consecutive crop-growing seasons in 2021 and 2022. The study aimed to identify lines with both high stable yields and enhanced resistance to anthracnose disease for potential release and utilization in future bean varietal development in Uganda. Agronomic traits, including days to 50% flowering, days to 90% physiological maturity, seed yield, seed yield components, and anthracnose disease reaction under natural infestation were assessed. The response to anthracnose disease was further assessed using six isolates of Colletotrichum lindemuthianum representing six different races. Results indicated that the agronomic performances of the MAS backcross-derived bush bean lines were statistically comparable to the recurrent parent NABE14. Specifically, six lines exhibited statistically equal to or higher performance than NABE14 in terms of seed yield, total number of seeds and number of pods per plant. The combined analysis of variance for seed yield showed significant (p Co-42 and Co-5 anthracnose resistance genes in the derived line. In conclusion, UGKT-B157-4, identified as the best-performing and stable genotype, demonstrates promise for release and use in future bean varietal development in Uganda, offering a combination of high yields and enhanced anthracnose disease resistance. The study provides valuable insights into the potential of Marker-Assisted Backcrossing in improving common bean varieties in the region.

Performance and yield stability of maize hybrids in stress-prone environments in eastern Africa

Identification and deployment of high-yielding and stress-tolerant maize hybrids adapted to stress-prone agro-ecologies is important for improving the food security and livelihoods of smallholder farmers in eastern Africa.The objectives of this study were to(i)assess the performance of maize hybrids under well-watered and drought stress conditions;(ii)evaluate grain yield stability of 65 intermediate-maturing and 55 early-maturing hybrids in 24 well-watered locations and seven drought stress locations;and(iii)identify representative and/or discriminative testing locations for increasing genetic gains for the target traits.There were significant differences for grain yield among early-and intermediatematuring hybrids tested under well-watered and drought stress environments.Among the early-maturing hybrids,the top 10 hybrids produced 46.8%–73.9%and 31.2%–42.1%higher mean grain yields than the best commercial check under drought and well-watered conditions,respectively.Among the intermediate-maturing hybrids,the top 10 hybrids produced 25.2%–47.7%and 8.5%–13.5%higher grain yield than commercial checks under drought stress and well-watered conditions,respectively,suggesting improvement in the levels of drought tolerance in both early-and intermediate-maturing hybrids.GGE biplot analysis and a bi-segmented regression linear method identified specific early-maturing and intermediate-maturing hybrids that performed well under both well-watered and drought stress conditions.These hybrids could be recommended for commercial production in eastern Africa.Kakamega in Kenya was found to be the most representative and highly discriminating site among well-watered testing locations,while Kabuku in Tanzania was the least representative of test locations.For testing under drought stress conditions,Kiboko in Kenya was identified as the most representative location.This information could be useful for allocating resources and streamlining CIMMYT maize hybrid testing in eastern Africa.

Profitability of Improved versus Traditional Cultivation Practices for African Indigenous Vegetables

Vegetables are important for nutrition and income of rural and urban households.However,vegetable consumption in Uganda is below World Health Organization(WHO)recommended guidelines,partly due to low production.The persistent low production arises from poor cultivation methods,low soil fertility,poor quality seed,pests and diseases,among others.This study compared the profitability of improved cultivation methods for African indigenous vegetables(AIVs),i.e.,pure stand and in lines,versus traditional practice(mixing seeds of different AIVs then broadcast),both for leafy and seed production.The AIVs included:Nakati(Solanum aethiopicum L.),Bugga(Amaranthus blitum L.)and Jobyo(Gynadropsis gynandra L.),arranged in completely randomized(CR)design with three replicates.Results showed that Nakati was more profitable when grown for leafy compared to seed production with benefit:cost ratio(BCR)9.2 and 4.0 for leafy and seed,respectively.Bugga for seed was more profitable compared to leafy production(BCR 18.0 and 2.7 for seed and leafy,respectively).Growing Jobyo for seed was more profitable than leafy production(BCR 14.9,2.4 for seed and leafy,respectively).Growing indigenous vegetables(IVs)for seed in mixed broadcast system,out of the three IVs farmers stand to economically maximize benefits for one crop(BCR 0.9,1.7 and 10.2 for Bugga,Nakati and Jobyo,respectively)compared to pure stand and in lines(BCR 18.0,4.2 and 14.9 for Bugga,Nakati and Jobyo,respectively).Thus,famers stand to benefit more if they grow IVs as pure stand and in lines as opposed to mixed and broadcast,whether for leafy or seed production.